This invention relates to .alpha.-diazoacetoacetates remarkably useful as a photosensitizer, precursors thereof, and photosensitive resin compositions prepared with the .alpha.-diazoacetoacetates suitable for lithography using KrF excimer laser (249 nm).
Diazoketone compounds containing one or more aromatic rings have been used as a sensitizer sensitive to a light (300 nm or more) in a resist. But these compounds are generally poor in sensitivity to a light of less than 300 nm. On the other hand, 5-diazo-Meldrum's acid and derivatives thereof which do not possess any aromatic rings are sensitive to a light of 300 nm or less [B.D. Grant et al.: IEEE Transactions on Electron Devices, vol. ED-28, No. 11, pp. 1300-1305 (1981)]. The 5-diazo-Meldrum's acid and derivatives thereof are excellent in bleaching but poor in solubility with a problem of having subliming properties.
Therefore, practically usable sensitizers overcoming the defects of known compounds have been desired.